This invention generally relates to a pump for inflating a prostheses and more particularly to a pump and valve assembly including a diaphragm which inhibits spontaneous inflation of the prosthesis.
One common treatment for male erectile dysfunction is the implantation of a penile prosthesis. Such a prosthesis typically includes a pair of inflatable cylinders which are fluidly connected to a fluid reservoir via a pump and valve assembly. The two cylinders are normally implanted into the corpus cavernosae of the user and the reservoir is typically implanted in the user's abdomen. The pump assembly is implanted in the scrotum. During use, the user actuates the pump and fluid (typically liquid) is transferred from the reservoir through the pump and into the cylinders. This results in the inflation of the cylinders and thereby produces the desired penis rigidity for a normal erection. Then, when the user desires to deflate the cylinders, a valve assembly within the pump is actuated in a manner such that the fluid in the cylinders is released back into the reservoir. This deflation then returns the penis to a flaccid state.
With inflatable penile prostheses of current designs, spontaneous inflation of the cylinders is known to occasionally occur due to inadvertent compression of the reservoir. Specifically, this inadvertent compression results in the undesired introduction of fluid into the cylinders. While this does not create a medical or physical problem, such inadvertent inflation can be uncomfortable and embarrassing for the user. This undesirable condition is further described below with reference to a particular prosthetic design.
With reference to FIG. 1, a known pump and valve assembly 8 for use in a penile prosthesis includes a fluid input 10 that is coupled at one end to a reservoir (not shown) and to a housing 12 at its opposite end. Also connected to the housing 12 is a fluid output 14 which, in turn, is connected at its other end to a pair of cylinders (not shown). Linking the fluid input 10 and the fluid output 14 to each other is a common passageway 33, which itself contains a valve assembly that is described in greater detail below. Common passageway 33 is also in fluid communication with a pump bulb 18 that is used to move fluid from the reservoir (not shown) to the cylinders (not shown) in order to inflate the cylinders. The valve assembly located within common passageway 33 includes a reservoir poppet 20 which is biased against a valve seat 24 by a spring 28 and a cylinder poppet 22 which is biased against a valve seat 26 by a spring 30. The springs 28 and 30 are sized so as to keep the reservoir poppet 20 and the cylinder poppet 22 biased against each respective valve seat 24 and 26 under the loads that are encountered when the reservoir is pressurized to typical abdominal pressures.
When the user wishes to inflate the cylinders, pump bulb 18 is squeezed so as to force fluid from the pump bulb 18 into the common passageway 33. The resulting fluid flow creates a fluid pressure on reservoir poppet 20 which compliments the force of the spring 28 to hold the reservoir poppet 20 against valve seal 24. The fluid flow also causes compression of the spring 30, and thereby opening cylinder poppet 22. As a result, the fluid travels out through fluid output 14 and into the respective cylinders.
When the user releases the pump bulb 18 a vacuum is created, thus pulling the poppet 22 back against valve seat 26 (aided by spring 30) and simultaneously pulling the reservoir poppet 20 away from its valve seat 24, against the spring 28. As a result, fluid from the reservoir is thus allowed to flow through the fluid input 10 to the common passageway 33, passing around the reservoir poppet 20. Fluid then will freely flow into the vacuous pump bulb 18. Once the pump bulb 18 has been filled, the negative pressure is eliminated and the reservoir poppet 20 returns to its normal position. This pumping action of the pump bulb 18 and valve assembly is repeated until the cylinders are fully inflated as desired.
To deflate the cylinders, the user grips the housing 12 and compresses it along the axis of reservoir poppet 20 and cylinder poppet 22 in a manner such that the wall 13 of the housing 12 contacts the protruding end 21 of the reservoir poppet 20 and forces the reservoir poppet 20 away from valve seat 24. This movement, in turn, causes the reservoir poppet 20 to contact cylinder poppet 22 and force cylinder poppet 22 away from valve seat 26. As a result, both poppets 20 and 22 are moved away from their valve seats 21 and 26 and fluid moves out of the cylinders, through the fluid output 14, through common passageway 33, through the fluid input 10 and back into the reservoir.
Although the springs 28 and 30 are sized to provide sufficient tension to keep poppets 20 and 22 firmly abutted against valve seats 24 and 26 under normal reservoir pressures, it is possible for fluid pressure to exceed the force provided by the springs during heightened physical activity or movement by the user. Specifically, this activity or movement can apply excess pressure to the reservoir. Such excessive pressure on the reservoir may overcome the resistance of the spring-biased poppets 20 and 22 and thereby cause a spontaneous inflation of the cylinders. Encapsulation or calcification of the reservoir can sometimes occur in a patient. This encapsulation could lead to a more snugly enclosed reservoir, thus increasing the possibility of providing excess pressure on the reservoir and the likelihood of spontaneous inflation.
As such, there exists a need to provide a prosthetic penile implant having a spontaneous inflation prevention mechanism that is reliable and easy to operate.